Why do you need weapons as an incantatrix? You have spells... Unless by weapons you mean magic items in general.
I've heard putting some passive weapon enchantments, like Warning and Eager (MIC), on both ends of a double weapon such as a quarterstaff can be an effective use of caster resources.
Also, a wand chamber (Dungeonscape) in both ends.
That would be the reason that I would grab a weapon. This is what I found ad was wanting to do:
A +1 Eager Spellstrike / +1 Warning Defending quarterstaff costs 36.600 gp and gives you a huge amount of bonuses (assuming magic weapon, greater is casted on both heads, with a rod of lesser chain for example).
+5 bonus to AC which stacks with all others.
+5 bonus on saving throws against spells and spell-like abilities (it has no type, so assume that it stacks with all others).
+7 bonus to initiative checks. (actually +5 insight and +2 unnamed).
But with my limitations I was looking for other spells to compensate. The books that are available to me are: DMG, PHB, MM, Forgotten Realms Campaign Setting, Players Guide to Faerun, Spell Compendium.